Methods and system for cleaning gas turbine engine

ABSTRACT

A method for cleaning components of a gas turbine engine is presented. The method includes introducing a working fluid into a gas flow path or a cooling circuit defined by the one or more components of the gas turbine engine such that the working fluid impinges upon a surface of the one or more components of the gas turbine engine, wherein the working fluid includes a plurality of detergent droplets entrained in a flow of steam. A system for cleaning components of a gas turbine engine are also presented.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/443,048 filed Feb. 27, 2017, which is hereby incorporated herein byreference in its entirety.

BACKGROUND

Embodiments of the disclosure generally relate to methods and system forcleaning components of gas turbine engines. More particularly,embodiments of the disclosure relate to methods and system for cleaningcomponents of gas turbine engines using a mixture of steam and atomizeddetergent.

Turbines, such as gas turbine engines, may typically intake foreignmaterial (e.g., particulate matter) during operation that may affect theperformance of the engines. Non-limiting examples of the foreignmaterial include dust (including mineral dust), sand, dirt, fly ash,volcanic ash, and runway debris.

For hot turbine engine components, foreign material compositions ofparticular concern are those containing oxides of calcium, magnesium,aluminum, silicon, and mixtures thereof. These oxides combine to formcontaminant compositions comprising mixedcalcium-magnesium-aluminum-silicon-oxide systems (Ca—Mg—Al—SiO),hereafter referred to as “CMAS.” At the high turbine operatingtemperatures, these environmental contaminants can adhere to the heatedcomponent surface, and thus cause damage to the structural integrity ofthe components that may result in premature component failure. Prematurecomponent failure can lead to unscheduled maintenance as well as partsreplacement resulting in reduced performance, and increased operatingand servicing costs.

Further, gas turbine engines, typically include internal coolingcircuits that are designed to cool one or more components during use.Ingestion and subsequent deposition of the foreign material in theseinternal cooling circuits may result in partial or complete blockage ofthe cooling circuits, thereby reducing the cooling efficiency of thecircuits. In addition to blocking or clogging the cooling circuits, theforeign material may also become deposited on the internal surfaces ofcooled components and create an insulating layer, thereby reducing thecooling efficiency and resulting in operating temperature increase andreduction of the component's life.

However, most of these turbine engine components are typically eithernot cleaned or cleaned through methods that are expensive, timeconsuming, labor intensive, or ineffective. For example, typical methodsof cleaning the engine components include water wash, dry ice treatment,or acid wash. Water wash and dry ice treatment are not very effective incleaning CMAS-based secondary reaction products. Acid wash treatmentsare generally only applied following engine disassembly in a servicerepair shop environment, as these acid solutions are not compatible withthe full suite of materials that comprise the assembled engine.Therefore, if using conventional cleaning methods, the turbine enginesmay need to be removed from service (e.g., detached from the aircraft,power plant or other machine that the engine powers or is otherwise usedwith) and substantially dismantled to provide direct access to thecomponents for cleaning. This significantly reduces time-on-wing andimpacts the operating and maintenance costs.

Therefore, there is a need for methods and systems of cleaning turbineengine components without substantially dismantling the engine, andwithout interfering with the structural and metallurgical integrity ofother components of the engine.

BRIEF DESCRIPTION

In one aspect, the disclosure relates to a method for cleaning one ormore components of a gas turbine engine. The method includes introducinga working fluid into a gas flow path or a cooling circuit defined by theone or more components of the gas turbine engine such that the workingfluid impinges upon a surface of the one or more components of the gasturbine engine, wherein the working fluid includes a plurality ofdetergent droplets entrained in a flow of steam.

In another aspect, the disclosure relates to a method for in-situcleaning of a cooling circuit defined by one or more components of a gasturbine engine. The method includes forming a working fluid including aplurality of detergent droplets entrained in a flow of steam, whereinthe plurality of detergent droplets is characterized by a sizedistribution that is effective to be substantially accommodated in thecooling circuit. The method further includes introducing the workingfluid into the cooling circuit such that the working fluid impinges upona surface of the one or more components of the gas turbine engine.

In yet another aspect, the disclosure relates to a system for cleaningone or more components of a gas turbine engine. The system includes afluid mixing unit configured to form a working fluid including aplurality of detergent droplets entrained in a flow of steam. The systemfurther includes a fluid delivery mechanism fluidly coupled with thefluid mixing unit, and configured to introduce the working fluid into agas flow path or a cooling circuit defined by the one or more componentsof the gas engine such that the working fluid impinges upon a surface ofthe one or more components of the gas turbine engine.

These and other features, embodiments, and advantages of the presentdisclosure may be understood more readily by reference to the followingdetailed description.

DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings,wherein:

FIG. 1 is a cross-sectional view of a gas turbine engine, in accordancewith some embodiments of the disclosure;

FIG. 2 illustrates a system for forming a working fluid, in accordancewith some embodiments of the disclosure;

FIG. 3 illustrates a system for forming a working fluid, in accordancewith some embodiments of the disclosure;

FIG. 4 illustrates a system for forming a working fluid, in accordancewith some embodiments of the disclosure;

FIG. 5 illustrates a method for cleaning a turbine engine, in accordancewith some embodiments of the disclosure;

FIG. 6 illustrates a method for cleaning a turbine engine, in accordancewith some embodiments of the disclosure;

FIG. 7 is an optical image of a section of a combustor liner showingdeposition of certain foulants in three areas marked area 1, area 2, andarea 3.

FIG. 8 Top row (A), (B) and (C) are optical images, and bottom row (D),(E) and (F) are X-ray fluorescence (XRF) scans showing calciumdistribution maps, and demonstrating the effects of the cleaning methodsdescribed herein on area 1 of the combustor liner section shown in FIG.7.

FIG.9 Top row (A), (B) and (C) are optical images, and bottom row (D),(E) and (F) are X-ray fluorescence (XRF) scans showing calciumdistribution maps, and demonstrating the effects of the cleaning methodsdescribed herein on area 2 of the combustor liner section shown in FIG.7.

FIG. 10 Top row (A), (B) and (C) are optical images, and bottom row (D),(E) and (F) are X-ray fluorescence (XRF) scans showing sulfurdistribution maps, and demonstrating the effects of the cleaning methodsdescribed herein on area 1 of the combustor liner section shown in FIG.7.

FIG. 11 Top row (A), (B) and (C) are optical images, and bottom row (D),(E) and (F) are X-ray fluorescence (XRF) scans showing sulfurdistribution maps, and demonstrating the effects of the cleaning methodsdescribed herein on area 2 of the combustor liner section shown in FIG.7.

DETAILED DESCRIPTION

In the following specification and the claims, which follow, referencewill be made to a number of terms, which shall be defined to have thefollowing meanings. The singular forms “a”, “an” and “the” includeplural referents unless the context clearly dictates otherwise. As usedherein, the term “or” is not meant to be exclusive and refers to atleast one of the referenced components being present and includesinstances in which a combination of the referenced components may bepresent, unless the context clearly dictates otherwise.

Approximating language, as used herein throughout the specification andclaims, may be applied to modify any quantitative representation thatcould permissibly vary without resulting in a change in the basicfunction to which it is related. Accordingly, a value modified by a termor terms, such as “about”, and “substantially” is not to be limited tothe precise value specified. In some instances, the approximatinglanguage may correspond to the precision of an instrument for measuringthe value. Similarly, “free” may be used in combination with a term, andmay include an insubstantial number, or trace amounts, while still beingconsidered free of the modified term. Here and throughout thespecification and claims, range limitations may be combined and/orinterchanged, such ranges are identified and include all the sub-rangescontained therein unless context or language indicates otherwise.

Embodiments of the present disclosure relate to methods and systems ofcleaning one or more components of a gas turbine engine. In someembodiments, a method of cleaning includes introducing a working fluidinto a gas flow path or a cooling circuit defined by the one or morecomponents of the gas turbine engine such that the working fluidimpinges upon a surface of the one or more components of the gas turbineengine, wherein the working fluid includes a plurality of detergentdroplets entrained in a flow of steam.

A gas turbine engine refers to any turbine engine in which the turbineis driven by the combustion products of air and fuel. In someembodiments, the gas turbine engine may be an aircraft engine.Alternatively, the gas turbine engine may be any other type of engineused in industrial applications. Non -limiting examples of such gasturbine engines include a land-based gas turbine engine employed in apower plant, a gas turbine engine used in a marine vessel, or a gasturbine engine used in an oil rig. The terms “gas turbine engine” and“turbine engine” are used herein interchangeably.

FIG. 1 is a schematic view of a representative gas turbine engine 10 inaccordance with some embodiments of the disclosure. The gas turbineincludes a fan assembly 12 and a core engine 13 including ahigh-pressure compressor 14, a combustor 16, a high-pressure turbine(HPT) 18, and a low-pressure turbine (LPT) 20. Fan assembly 12 includesan array of fan blades 24 that extend radially outward from a rotor disk26. Engine 10 has an intake side 28 and an exhaust side 30. Fan assembly12 and LPT 20 are coupled by a low-speed rotor shaft 31, and compressor14 and HPT 18 are coupled by a high-speed rotor shaft 32.

Generally, in operation, air flows axially through fan assembly 12, in adirection that is substantially parallel to a centerline 34 that extendsthrough engine 10, and compressed air is supplied to high pressurecompressor 14. The highly compressed air is delivered to combustor 16.Combustion gas flow (not shown) from combustor 16 drives turbines 18 and20. HPT 18 drives compressor 14 by way of shaft 32 and LPT 20 drives fanassembly 12 by way of shaft 31.

As noted earlier, the method and systems disclosed herein provide forcleaning of a foreign material deposited on one or more components ofthe turbine engine. The foreign material may be any material, such asparticulate material, that is built up, introduced, or produced on or inone or more components of the turbine engine during operation of theturbine engine. In some embodiments, the foreign material may be anymaterial that is deposited and/or produced on components of the turbineengine after initial manufacture of the turbine that decreases theefficiency of the turbine or otherwise interferes with or degrades oneor more function or component of the turbine.

Non-limiting examples of the foreign material include dust (includingmineral dust), sand, dirt, fly ash, volcanic ash, runway debris, or anyother material or pollutant that is ingested or otherwise introducedinto the engine and deposited or adhered onto one or more components.The foreign material that is cleaned using the methods and systemsdescribed herein may also include one or more of the aforementionedmaterials that have reacted or been otherwise altered by the heat,pressure, etc. within the engine. In some embodiments, the foreignmaterial is a combination of soluble and insoluble dust species thathave been ingested by a turbine engine and deposited (e.g., built upover time) on one or more components.

In some embodiments, the methods and systems disclosed herein providefor cleaning of CMAS-based reaction products. The term “CMAS” as usedherein refers to a contaminant composition including calcium, magnesium,aluminum and silicon, resulting from the ingestion of siliceous minerals(e.g., dust, sand, volcanic ash, fly ash, cement, runway dirt, and thelike) in gas turbine engines. The compositional characteristics of theCMAS-based reaction product may depend, in part, on one or more of thesource of the environmental contaminants, the reaction temperature,location of the foreign material within sections of the turbine engine,or the operational environment of the turbine engine.

Non-limiting examples of turbine engine components that may be cleanedby the methods and systems disclosed herein include, but are not limitedto, shrouds, buckets, blades, nozzles, vanes, combustor liners, sealcomponents, and rotors.

As mentioned previously, to effect cleaning of the components, a workingfluid is introduced into a gas flow path or a cooling circuit defined bythe one or more components of the gas turbine engine such that theworking fluid impinges upon a surface of the one or more components ofthe gas turbine engine. In some embodiments, the working fluid isintroduced into at least one gas flow path in the gas turbine engine. Insome embodiments, the working fluid is introduced into at least onecooling circuit in the gas turbine engine. In some embodiments, theworking fluid is introduced into at least one gas flow path and at leastone cooling circuit in the gas turbine engine.

The term “gas flow path” as used herein refers to one or more of acompressor flow path, a hot gas path in the combustor section, a hot gaspath in the turbine section of the engine (HPT or LPT), or a secondarycooling flow path e.g., flow path between the casing and the combustorliner. The compressor flow path and the hot gas path (in the combustorsection or the turbine section) may also be referred to as the core flowpath. Therefore, in some embodiments, the working fluid may beintroduced into one or more of the compressor flow path, the hot gaspath in the combustor section, the hot gas path in the turbine sectionof the engine (HPT or LPT), or the secondary cooling flow path betweenthe casing and the combustor liner, to effect cleaning of the turbineengine components defining these flow paths.

Cleaning by introducing the working fluid into the compressor flow pathor the secondary cooling flow path may also be referred to as cleaningof the cold sections of the turbine engine. Similarly, cleaning byintroducing the working fluid into the hot gas path in the combustorsection or a hot gas path in the turbine section of the engine (HPT orLPT) may also be referred to as cleaning of the hot sections of theturbine engine. As will be appreciated by one of ordinary skill in theart, by introducing the working fluid into the appropriate gas flowpath, cleaning of the turbine engine component that has been fouled maybe effected. For example, to clean the compressor blades, the workingfluid may be introduced into the compressor flow path. Similarly, toclean the turbine (LPT or HPT) blades, the working fluid may beintroduced into the hot gas path in the turbine section.

The term “cooling circuit” as used herein refers to internal passages,film holes, or bores in the turbine engine components that are designedand configured to cool these components during use. The cooling circuitsmay be configured to cool the turbine engine components by convectioncooling, by impingement cooling, by film cooling, or combinationsthereof. In certain embodiments, the methods and systems describedherein are suitable for cleaning of internal passages of a turbineblade.

The term “working fluid” as used herein refers to a mixture of steam anddetergent, which is capable of selectively dissolving one or moreconstituents of the foreign material. As mentioned previously, theforeign material may include one or more of CMAS-based reactionproducts, interstitial cement, or mineral dust accumulated on theturbine components. In some embodiments, the working fluid is capable ofselectively dissolving one or more of oxide-based, chloride-based,sulfate-based, and carbon-based constituents of the foreign material.

More specifically, the working fluid includes a detergent that iscapable of selectively dissolving the constituents of the foreignmaterial. As used herein, the term “selectively dissolve” refers to anability of the detergent to be reactive with certain predeterminedmaterials, and to be substantially unreactive with materials other thanthe predetermined materials. Specifically, the term “selectivelydissolve” as used herein refers to a detergent that reacts with foreignmatter accumulated on underlying turbine components to facilitateremoval of the foreign material, but that is substantially unreactivewith the material used to form the underlying turbine components tolimit damage to them during removal of the foreign matter (i.e., duringa cleaning operation).

A suitable detergent for the methods and systems described herein mayinclude any detergent that conforms with Aerospace MaterialSpecification (AMS) 1551 a. In some embodiments, the detergent is formedby diluting a commercially available reagent composition to a desiredstrength prior to use as a working fluid. The dilution factor for thereagent composition in the detergent may be based on Federal AviationAdministration (FAA) guidelines. The FAA regulations provide acceptableelemental thresholds for compositions introduced into a turbine engine.In some embodiments, the reagent composition is diluted by a factor ofup to about 75 to form the detergent.

The reagent composition used to form the detergent may include a mixtureof water, an acid and water-based cleaning reagent, a surfactant, and anamine, for example, an alkanol amine. It is believed, without beingbound by any particular theory, that the acid component of the detergentis a primary driver that facilitates selective dissolution of theoxide-based, chloride-based, sulfate-based, and carbon-basedconstituents of the foreign material. Representative acid componentsinclude, but are not limited to, citric acid, glycolic acid, polyacrylic acid, and combinations thereof. In certain embodiments, areagent composition suitable for the methods and systems describedherein is disclosed in co-pending U.S. patent application publication2016/0024438, which disclosure is incorporated herein by reference.

In some embodiments, the detergent may include a mixture of water, anacid and water-based cleaning reagent, an organic surfactant, and acorrosion inhibitor. The detergent is designed to selectively dissolvesulfate, chloride and carbonate based species of foreign matter onturbine components while being substantially unreactive with thematerial forming the turbine components. In some embodiments, thedetergent may further optionally include a pH buffer. In certainembodiments, a reagent suitable for the methods and systems describedherein is disclosed in co-pending U.S. patent application publication2016/0024438, which disclosure is incorporated herein by reference.

In certain embodiments, a suitable reagent composition includes waterwithin a range between about 50 percent and about 70 percent by volumeof the reagent composition, glycolic acid within a range between about 5percent and about 15 percent by volume of the reagent composition,citric acid within a range between about 5 percent and about 15 percentby volume of the reagent composition, triethanol amine within a rangebetween about 1 percent and about 5 percent by volume of the reagentcomposition, alcohol alkoxylate within a range between about 1 percentand about 5 percent by volume of the reagent composition, andisopropylamine sulfonate within a range between about 1 percent andabout 10 percent by volume of the reagent composition. In someembodiments, the detergent is formed by diluting the reagent compositionwith water by a factor of up to about 75. The dilution is the effectedsuch that a sulfur concentration is maintained below a permissiblelimit. In some such embodiments, the detergent may further include a pHbuffer (for example, imidazole) and a corrosion inhibitor (for example,sodium lauriminodipropionate).

The detergent may be further characterized by it's pH. In someembodiments, the detergent has a pH in a range from about 2.5 to about10. In some embodiments, the detergent has a pH in a range from about2.5 to about 7. In some embodiments, the detergent has a pH in a rangefrom about 5 to about 7. In some embodiments, the detergent has a pH ofabout 5.5.

As used herein, the term “steam” refers to wet steam or dry steam. Thatis, the steam may be as a two-phase mixture of water vapor and entraineddroplets of water condensed from the water vapor, or, alternately thesteam may be composed of water vapor alone. Thus, the working fluidincludes a mixture of a detergent and steam where the steam is vapor or,alternatively, the steam is a combination of vapor and liquid. In someembodiments, steam may be superheated and pressurized prior to mixingwith the atomized detergent. In some embodiments, steam may becharacterized by temperature and water content such that aftertransferring heat to the detergent, it does not have a high-waterdroplet content and the detergent concentration is not substantiallyaltered. In some embodiments, steam may be superheated to a temperaturein a range up to 250° C.

In some embodiments, the method further includes atomizing the detergentin an atomizing nozzle and forming the working fluid. In someembodiments, the method further includes forming the working fluid bycontacting the steam with the detergent. In certain embodiments, thedetergent is atomized in an atomizing nozzle and the working fluid isformed by atomizing the detergent using steam in the atomizing nozzle.In some other embodiments, the working fluid is formed by mixing theatomized detergent with steam after the atomizing step.

Referring now to FIGS. 3 and 5, a system 100 and a method 1000 forcleaning a gas turbine engine in accordance with one embodiment isillustrated. As shown in FIGS. 3 and 5, in some embodiments, at step1001, the detergent 101 is introduced into an atomizing nozzle 250 alongwith steam 102. The detergent is atomized in the atomizing nozzle 250,at step 1002. At step 1003, a working fluid 103 is formed that includesa plurality of detergent droplets 104 (also referred to as atomizeddetergent 104) entrained in a flow of steam 102. As mentionedpreviously, in some such embodiments, the detergent 101 may be atomizedusing steam 102 in the atomizing nozzle 250 to form the working fluid103. In the embodiments illustrated in FIG. 3, the detergent and steamare introduced through separate inlets of the atomizing nozzle 250.However, embodiments wherein the steam and detergent are pre-mixed andthen introduced into atomizing nozzle via the same inlet are also withinthe scope of the present disclosure. The working fluid is 103 is furtherdischarged into a fluid delivery mechanism 300, at step 1004. As notedpreviously, the method further includes, at step 1005, introducing theworking fluid 103 into the gas flow path or the cooling circuit of theturbine engine by any suitable delivery mechanism 300.

Referring now to FIGS. 4 and 6, a system 100 and a method 2000 forcleaning a gas turbine engine in accordance with another embodiment isillustrated. As shown in FIGS. 4 and 6, in some embodiments, thedetergent 101 is first introduced into an atomizing nozzle at step 2001.At step 2002, the detergent is atomized in the atomizing nozzle 250 toform an atomized detergent 104. The method 2000 further includesdischarging the atomized detergent 104 into a flow of steam 102, at step2003. The atomized detergent 104 is mixed with steam 102 after the stepof atomizing to form the working fluid 103, at step 2004. In theembodiment illustrated in FIGS. 4 and 6, the method 2000 may furtherinclude introducing a suitable fluid (e.g., high pressure air) 105 intothe atomizing nozzle 250 to form the atomized detergent 104. The workingfluid is 103 is further discharged into a fluid delivery mechanism 300,at step 2005. As noted previously, the method further includes, at step2006, introducing the working fluid 103 into the gas flow path or thecooling circuit of the turbine engine by any suitable delivery mechanism300.

The method further includes controlling a size distribution of theplurality of detergent droplets in the working fluid such that the sizedistribution is effective to be substantially accommodated in the gasflow path or the cooling circuit. The term “substantially accommodated”as used herein means that the size distribution is controlled such thatthe plurality of detergent droplets can enter and follow the gas flowpath or the cooling circuit, and impact on surfaces that need to becleaned. Inventors of the present disclosure have recognized anddetermined that by controlling the size distribution of the plurality ofdetergent droplets in the working fluid effective cleaning may beachieved.

The size distribution of the plurality of detergent droplets istherefore carefully controlled depending on the component that requirescleaning. For example, a size distribution required for cleaning a gasflow path may be different from that of the size distribution requiredfor cleaning a cooling circuit. Similarly, even for cleaning a coolingcircuit, for example, the size distribution may be controlled dependingon the location and size of the cooling circuit.

In some embodiments, the method includes controlling a size distributionof the detergent droplets such that the detergent droplets may besubstantially accommodated in a gas flow path of the turbine engine. Insome embodiments, 50 percent of the plurality of detergent droplets ischaracterized by a size smaller than 500 microns. In some embodiments,75 percent of the plurality of detergent droplets is characterized by asize smaller than 500 microns. In some embodiments, 90 percent of theplurality of detergent droplets is characterized by a size smaller than500 microns. In some embodiments, 50 percent of the plurality ofdetergent droplets is characterized by a size smaller than 250 microns.In some embodiments, 75 percent of the plurality of detergent dropletsis characterized by a size smaller than 250 microns. In someembodiments, 90 percent of the plurality of detergent droplets ischaracterized by a size smaller than 250 microns.

In some embodiments, the method includes controlling a size distributionof the detergent droplets such that the detergent droplets may besubstantially accommodated in a cooling circuit of the turbine engine.In some embodiments, 50 percent of the plurality of detergent dropletsis characterized by a size smaller than 100 microns. In someembodiments, 75 percent of the plurality of detergent droplets ischaracterized by a size smaller than 100 microns. In some embodiments,90 percent of the plurality of detergent droplets is characterized by asize smaller than 100 microns.

Inventors of the present disclosure have recognized and determined thatthe size distribution of the plurality of detergent droplets isdependent at least in part on one or more of a detergent flow rate, asteam pressure, or an atomizing nozzle geometry. Therefore, methods andsystems as described herein include varying one or more of a detergentflow rate, a steam pressure, or an atomizing nozzle geometry to controlthe size distribution of the plurality of detergent droplets.

In some embodiments, a method for in-situ cleaning of a cooling circuitdefined by one or more components of a gas turbine engine is alsopresented. The method includes forming a working fluid that includes aplurality of detergent droplets entrained in a flow of steam. Theplurality of detergent droplets is characterized by a size distributionthat is effective to be substantially accommodated in the coolingcircuit, as described herein previously. The method further includesintroducing the working fluid into the cooling circuit such that theworking fluid impinges upon a surface of the one or more components ofthe gas turbine engine.

In some embodiments, the detergent may be further heated before theatomizing step. In some embodiments, the method includes heating thedetergent before the step of contacting with steam. In some suchinstances the detergent may be heated using any suitable heating mediumor mechanism. In some embodiments, the method includes heating thedetergent by contacting the detergent with steam. In some suchinstances, the steam also works as the heat source to generate dropletsin the temperature range where cleaning effectiveness is maximized.Referring again to FIG. 3, for example, the detergent 101 may be heatedby contacting the detergent with steam 102. In the embodimentsillustrated in FIG. 3, the detergent is heated by coaxially flowing thedetergent through two flows of steam 102. Other configurations are alsowithin the scope of the disclosure. Alternatively, for embodimentsdepicted in FIG. 4, the detergent may be heated using any other suitablemedium or mechanism. In the embodiments illustrated in FIG. 4, thedetergent may be heated before being introduced into the atomizingnozzle, or, may be heated in the atomizing nozzle itself prior to theatomizing step (e.g., using hot air).

In some embodiments, the method may include controlling the totalquality of the working fluid. The total quality of the working fluid isdefined as the ratio of the mass of the vapor content to the total massof the working fluid. The total quality is specified such that aftermixing steam and detergent, the detergent concentration is notsubstantially altered. In some embodiments, the working fluid qualitymay be in a range of 0.05 to 1.0.

In some embodiments, the quality of the working fluid is controlled byheating the detergent to a temperature in a range from about 40° C. toabout 130° C. In some embodiments, the detergent may be heated to atemperature in a range from about 60° C. to about 100° C.

In some embodiments, the working fluid quality is controlled bycontrolling the steam quality and temperature, which may include dry,wet and superheated steam states. In some embodiments, the steam qualitybefore mixing with the detergent is in the range of 0.2 to 1.0. Incertain embodiments, the superheated steam temperature may be in a rangefrom about 101° C. to about 250° C.

The cleaning methods and systems described herein employ a combinedthermal and rinsing effect of steam along with the cleaning effect ofdetergent to effect cleaning of the turbine engine components. Withoutbeing bound by any theory, it is believed that by using a mixture ofsteam and atomized detergent, the detergent amount required to clean thecomponents, the cycle time for cleaning, and the heating requirementsfor the detergent may significantly reduce. Further, the methods andsystems described herein may provide for an enhanced coverage of theturbine engine components with the detergent. This is in contrast toconventional cleaning systems that use air atomized detergents, orsequential application of steam and detergent.

After the step of forming the working fluid, the working fluid may beintroduced into the gas flow path or the cooling circuit through one ormore access ports or apertures in the turbine. Non-limiting examples ofsuitable access ports or apertures include, borescope apertures, burnerapertures, pressure sensor ports, fuel nozzle apertures, or combinationsthereof. In some embodiments, the working fluid may be introduced intothe gas flow path or the cooling circuit without substantial disassemblyof the turbine engine. In certain embodiments, the working fluid isintroduced into the gas flow path or the cooling circuit through atleast one borescope inspection port of the gas turbine engine.

In some embodiments, the working fluid is introduced into the turbineengine such that the working fluid impinges on the surface of one ormore components to be cleaned. For example, as mentioned earlier, insome embodiments the methods and systems described herein may be usedfor cleaning compressor blades. In such instances, the working fluid maybe introduced into the compressor flow path such that the working fluidimpinges on a soiled surface of the compressor blades. Similarly, insome embodiments, the methods and systems described herein may be usedfor cleaning a combustor liner. In such instances, the working fluid maybe introduced into the secondary cooling flow path such that the workingfluid impinges on a soiled surface of the combustor liner. In somefurther embodiments, the methods and systems described herein may beused for cleaning internal cooling passages of a turbine blade. In suchinstances, the working fluid may be introduced into the internal coolingpassages such that the working fluid impinges on a soiled inner surfaceof the turbine blade.

In some embodiments, the working fluid is introduced at a flow rate in arange from about 10 standard cubic feet per hour (SCFH) to about 2000SCFH. In some embodiments, the working fluid is introduced at a flowrate in a a range from about 20 standard cubic feet per hour (SCFH) toabout 1000 SCFH.

In some embodiments, the gas turbine engine is a fully assembled gasturbine engine, or a sub-assembly of a gas turbine engine and thecleaning is effected without disassembly of the engine. In someembodiments, the sub-assembly of the turbine engine which is cleaned isthe compressor section/module or the combustion section/module. In someembodiments, the sub-assembly of the turbine engine which is cleaned isthe booster assembly/module, the high-pressure turbine assembly/module,or the low-pressure turbine assembly/module.

In some embodiments, the methods and systems described herein allow forin-situ cleaning of a gas turbine engine. The term “in-situ” cleaning ofa gas turbine engine means that the gas turbine engine is asubstantially assembled state and not detached from the aircraft or isinstalled in an industrial application (e.g., in a power plant, a marinevessel, an oil rig, pump, and the like). In some embodiments, the gasturbine engine is disposed on an aircraft, and the cleaning is effectedon wing. In some embodiments, the gas turbine engine is installed in anindustrial application. Non-limiting examples of industrial applicationsinclude power plants, marine vessels, oil rigs, pumps, and the like.

A system for cleaning one or more components of a gas turbine engine isalso presented. A system 100 in accordance with some embodiments of thedisclosure is illustrated in FIG. 2. As shown in FIG. 2, the system 100includes a fluid mixing unit 200 configured to form a working fluid 103including a plurality of detergent droplets 104 entrained in a flow ofsteam 102. The fluid mixing unit 200 is configured to form the workingfluid 103 by atomizing the detergent 101 and mixing the atomizeddetergent with steam 102. The system 100 further includes a fluiddelivery mechanism 300 fluidly coupled with the fluid mixing unit 200,and configured to introduce the working fluid 103 into a gas flow pathor a cooling circuit defined by the one or more components of the gasengine (not shown in FIG. 2), such that the working fluid impinges upona surface of the one or more components of the gas turbine engine.

The term “fluid mixing unit” as used herein refers to a component orcombination of components capable of forming detergent droplets andmixing the atomized detergent with steam. Therefore, the fluid mixingunit may include one or more components capable of forming detergentdroplets. Non-limiting example of such a component includes an atomizingnozzle. The fluid mixing unit may further include one or more conduitsfor delivering one or more of detergent, pressurized air, or steam intothe atomizing nozzle, for example. The fluid mixing unit may furtherinclude one or more conduits for discharging the atomized detergent orthe working fluid from the atomizing nozzle, for example. In someembodiments, the fluid mixing unit may further include suitable fluidcontrol mechanisms such as valves to control the flow into or out of theatomizing nozzle.

The term “fluid delivery mechanism” as used herein refers to a unitcapable of delivering the working fluid from the fluid mixing unit tothe gas flow path or the cooling circuit of the turbine engine.Non-limiting examples of suitable fluid delivery mechanism includeconduits, tube, pipes, and the like.

In some embodiments, as illustrated in FIG. 3, the fluid mixing unit 200includes an atomizing nozzle 250 configured to (i) receive a detergent101, (ii) receive steam 102, (iii) form the working fluid 103 byatomizing the detergent using steam, and (iv) discharge the workingfluid 103 into the fluid delivery mechanism 300.

In some embodiments, as illustrated in FIG. 4, the fluid mixing unit 200includes an atomizing nozzle 250 configured to (i) receive a detergent101, (ii) atomize the detergent, and (iii) discharge the atomizeddetergent 104 into a flow of steam 102 to form the working fluid 103.The working fluid 103 as shown in FIG. 4 may be further discharged intothe fluid delivery mechanism 300. As noted previously, the fluiddelivery mechanism is fluidly coupled with a gas flow path or a coolingcircuit of a gas turbine engine. In some embodiments, the gas flow pathis a hot gas path of the gas turbine engine and the fluid deliverymechanism 300 is fluidly coupled with the hot gas path (not shown). Insome embodiments, the fluid delivery mechanism 300 is fluidly coupledwith the cooling circuit of the gas turbine engine (not shown). Asmentioned previously, the fluid delivery mechanism 300 may be fluidlycoupled with the gas flow path or the cooling circuit via one or moreaccess ports or apertures in the turbine engine.

An exemplary technical effect of the methods and systems, describedherein, includes at least one of (a) enabling in-situ cleaning ofturbine engines; (b) selectively dissolving foreign material havingdifferent elemental compositions from materials of general turbineengine constructions; and (c) reducing downtime of the turbine enginescleaned by the methods described herein. Further, advantageously, inaccordance with some embodiments of the disclosure, the methods andsystems described herein are environmentally friendly and non-toxic, andcan be employed without the need for specialized ventilation orventilated spaces such as hoods, or, any expensive personal protectiveequipment for technicians effecting the cleaning.

EXAMPLES Example 1 Forming the Working Fluid including Steam AtomizedDetergent

A detergent composition as described in US patent applicationpublication 2016/0024438 (Reagent 6) was heated to 92° C., and passedthrough Teflon-lined tubing at a flow rate of 75 mL/minute using aperistaltic pump into an atomizing nozzle that was simultaneouslyflowing 300° F. (148.8° C.) steam at 4 SCFH (standard cubic feet hour)to generate a mixture of steam and atomized detergent (working fluid).

Example 2 Cleaning a Fouled Turbine Engine Component (Combustor Liner)with the Working Fluid

The working fluid formed in Example 1 was contacted with a fouledsurface of a combustor liner as an example of flow path cleaning.Referring to FIG. 7, an optical image of a portion of a combustor linerfrom HPT 18 section of turbine engine 10 (shown in FIG. 1) shows foulingin certain areas, marked as areas 1, 2 and 3 in FIG. 7. Area 1 exhibitedCMAS deposition as a white streaked, continuous layer. Area 2 exhibitedintermediate, discontinuous layers of CMAS along with dust (sulfates andclay) fused on the thermal barrier coating (TBC) surface. Area 3exhibited dark brown, dust fused on the thermal barrier TBC surface withnegligible CMAS formation. The combustor liner was exposed to theworking fluid for 15 minutes to 4 hours.

The cleaning effectiveness of the working fluid on areas 1 and 2 wasdetermined using x-ray fluorescence (XRF) spectrometry. Referring toFIGS. 8 and 9, the XRF scans show calcium distribution maps anddemonstrate the effects of the cleaning methods described herein on area1 (FIG. 8) and area 2 (FIG. 9) of the fouled combustor liner mentionedabove. FIGS. 8 and 9, top row (A), (B) and (C) are optical images, andbottom row (D), (E) and (F) are XRF scans showing the calciumdistribution. The effect of 15 minutes and 4 hours of cleaning using theworking fluid formed in Example 1 was shown. A darker image (i.e., lowsignal) in the bottom row indicates effective cleaning (i.e., removal ofcalcium sulfate).

Referring to FIGS. 10 and 11, the XRF images show sulfur distributionmaps and demonstrate the effects of the cleaning methods describedherein on area 1 (FIG. 10) and area 2 (FIG. 11) of the fouled combustorliner mentioned above. FIGS. 10 and 11, top row (A), (B) and (C) areoptical images, and bottom row (D), (E) and (F) are XRF scans showingthe sulfur distribution. The effect of 15 minutes and 4 hours ofcleaning using the working fluid formed in Example 1 was shown. A darkerimage (i.e., low signal) in the bottom row indicates effective cleaning(i.e., removal of calcium sulfate).

Comparative Example 1: Cleaning a Fouled Turbine Engine Component(Combustor Liner) with only Steam

A fouled combustor liner (as described in Example 2) was contacted withsteam for 15 hours to determine the effective of cleaning with steam onits own. Cleaning effectiveness was determined using electron probemicroanalyzer (EMPA) and by determining the chemical composition(calcium, sulfur, magnesium and iron distribution) of the area that wascleaned before and after contacting with steam. As will be appreciatedby one of ordinary skill in the art, EMPA analysis proves full depthinformation for the sample being analyzed while μXRF provides surfaceanalysis. EMPA analysis of the area that was cleaned showed that theelements calcium, sulfur, magnesium and iron were present in the samplebefore as well as after contacting the sample with steam.

Comparative Example 2: Cleaning a Fouled Turbine Engine Component(Combustor Liner) with only Detergent

A fouled combustor liner (as described in Example 2) was contacted witha foamed detergent composition (as described in US patent applicationpublication 2016/0024438) for 15 hours to determine the effective ofcleaning with detergent on its own. Cleaning effectiveness wasdetermined using electron probe microanalyzer (EMPA) and by determiningthe chemical composition (calcium, sulfur, magnesium and irondistribution) of the area that was cleaned before and after contactingwith detergent. EMPA analysis of the area that was cleaned showed thatthe elements calcium, sulfur, magnesium and iron were present in thesample before as well as after contacting the sample with the detergent

Example 3 Cleaning a Fouled Turbine Engine Component (Combustor Liner)with a Mixture of Steam and Atomized Detergent

A fouled combustor liner (as described in Example 2) was contacted withthe working fluid of Example 1 for 15 hours to determine theeffectiveness of cleaning with a mixture of steam and atomized detergent(working fluid). Cleaning effectiveness was determined using electronprobe microanalyzer (EMPA) and by determining the chemical composition(calcium, sulfur, magnesium and iron distribution) of the area that wascleaned before and after contacting with steam and atomized detergent.EMPA analysis of the area that was cleaned showed that the elementscalcium, sulfur, magnesium and iron were present in the sample beforecontacting the sample with the working fluid. In contrast, the elementalconcentration of these elements was significantly reduced aftercontacting the sample with the working fluid. A measurable decrease inthe total thickness of the CMAS layer was also observed, therebydemonstrating that a mixture of steam and atomized detergent providesfor effective cleaning of dust-related deposits.

Example 4 Cleaning a Fouled Turbine Engine Component (HPT Stage 1Blades) with the Working Fluid

A detergent composition as described in US patent applicationpublication 2016/0024438 (Reagent 6) was heated to 80° C., and passedthrough Teflon-lined tubing at a flow rate of 100 mL/minute using aperistaltic pump into an atomizing nozzle that was simultaneouslyflowing 300° F. (148.8° C.) steam at 4 SCFH (standard cubic feet hour)to generate a mixture of steam and atomized detergent (working fluid).

The working fluid was contacted with a fouled surface of a HPT blade.This was replicated on three blades from the same rotor, and the averageairflow restoration was measured on the dirty blades and the cleanedblades. The average airflow restoration on the lead edge was 5% (cleanrelative to the dirty flow check). This indicated that the working fluidwas effective in cleaning the turbine blades. Examples 2-4 show that byusing steam atomized detergent, according to embodiments of theinvention, the flow path and the cooling circuits in a gas turbineengine can be effectively cleaned.

The foregoing examples are merely illustrative, serving to exemplifyonly some of the features of the invention. The appended claims areintended to claim the invention as broadly as it has been conceived andthe examples herein presented are illustrative of selected embodimentsfrom a manifold of all possible embodiments. Accordingly, it is theApplicants' intention that the appended claims are not to be limited bythe choice of examples utilized to illustrate features of the presentinvention. As used in the claims, the word “comprises” and itsgrammatical variants logically also subtend and include phrases ofvarying and differing extent such as for example, but not limitedthereto, “consisting essentially of” and “consisting of” Wherenecessary, ranges have been supplied; those ranges are inclusive of allsub-ranges there between. It is to be expected that variations in theseranges will suggest themselves to a practitioner having ordinary skillin the art and where not already dedicated to the public, thosevariations should where possible be construed to be covered by theappended claims. It is also anticipated that advances in science andtechnology will make equivalents and substitutions possible that are notnow contemplated by reason of the imprecision of language and thesevariations should also be construed where possible to be covered by theappended claims.

1. A method for cleaning one or more components of a gas turbine engine,comprising: introducing a working fluid into a gas flow path or acooling circuit defined by the one or more components of the gas turbineengine such that the working fluid impinges upon a surface of the one ormore components of the gas turbine engine, wherein the working fluidcomprises a plurality of detergent droplets entrained in a flow ofsteam.
 2. The method of claim 1, further comprising atomizing adetergent in an atomizing nozzle and forming the working fluid.
 3. Themethod of claim 1, wherein forming the working fluid comprisescontrolling a size distribution of the plurality of detergent dropletsin the working fluid such that the size distribution is effective to besubstantially accommodated in the gas flow path or the cooling circuit.4. The method of claim 3, wherein a 50 percent of the plurality ofdetergent droplets is characterized by a size smaller than 500 microns.5. The method of claim 3, wherein a 50 percent of the plurality ofdetergent droplets is characterized by a size smaller than 100 microns.6. The method of claim 3, comprising varying one or more of a detergentflow rate, a steam pressure, and an atomizing nozzle geometry to controlthe size distribution of the plurality of detergent particles in theworking fluid.
 7. The method of claim 2, wherein the working fluid isformed during the step of atomizing the detergent by using steam.
 8. Themethod of claim 2, wherein the working fluid is formed by mixing theatomized detergent with steam after the atomizing step.
 9. The method ofclaim 2, further comprising heating the detergent before the atomizingstep by contacting the detergent with steam.
 10. The method of claim 1,wherein the detergent has a pH in a range from about 2.5 to about
 7. 11.The method of claim 1, wherein the gas flow path is a hot gas path inthe gas turbine engine.
 12. The method of claim 1, wherein the gasturbine engine is disposed on an aircraft or installed in an industrialapplication.
 13. A method for in-situ cleaning of a cooling circuitdefined by one or more components of a gas turbine engine, comprising:forming a working fluid comprising a plurality of detergent dropletsentrained in a flow of steam, wherein the plurality of detergentdroplets is characterized by a size distribution that is effective to besubstantially accommodated in the cooling circuit; and introducing theworking fluid into the cooling circuit such that the working fluidimpinges upon a surface of the one or more components of the gas turbineengine.
 14. The method of claim 13, wherein a 50 percent of theplurality of detergent droplets is characterized by a size smaller than100 microns
 15. A system for cleaning one or more components of a gasturbine engine, comprising: a fluid mixing unit configured to form aworking fluid comprising a plurality of detergent droplets entrained ina flow of steam, a fluid delivery mechanism fluidly coupled with thefluid mixing unit, and configured to introduce the working fluid into agas flow path or a cooling circuit defined by the one or more componentsof the gas engine such that the working fluid impinges upon a surface ofthe one or more components of the gas turbine engine.
 16. The system ofclaim 15, wherein the fluid mixing unit comprises an atomizing nozzleconfigured to (i) receive a detergent, (ii) receive steam, (iii) formthe working fluid by atomizing the detergent using steam, and (iv)discharge the working fluid into the fluid delivery mechanism.
 17. Thesystem of claim 15, wherein the fluid mixing unit comprises an atomizingnozzle configured to (i) receive a detergent, (ii) atomize thedetergent, and (iii) discharge the atomized detergent into a flow ofsteam to form the working fluid.
 18. The system of claim 15, wherein thegas flow path is a hot gas path of the gas turbine engine and the fluiddelivery mechanism is fluidly coupled with the hot gas path.
 19. Thesystem of claim 15, wherein the fluid delivery mechanism is fluidlycoupled with the cooling circuit of the gas turbine engine.
 20. Thesystem of claim 15, wherein the gas turbine engine is disposed on anaircraft or installed in an industrial application